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devices or are kept up in the virtual network plane, which can be a
reproduction of the discovered physical connectivity or a simplified/
arbitrary version (e.g., single router abstractions [22,28]) of the HW
resources. In the former, messages follow the physical path, so no
additional fault-detection mechanism are required at the cost of
extra propagation delays. In the latter, signaling is kept in the virtual
domain, benefiting from low latencies and contributing to better scal-
ability. is option provides a more natural support for virtual networks
but requires extra programmability and fault-detection extensions to
update VMs’ logical associations caused by physica